Device for trisecting angles.



G. L. DENNIS.

DEVICE FOR TRISEGTING ANGLES. APPLICATION FILED 00130, 1913.

Patented Apr. 21, 1914,

2 SHEETSSHEET 1.

G. L. DENNIS.

DEVICE FOR TRISEGTING ANGLES.

APPLICATION FILED 00130, 1913.

1,093,91 9, 0 Patented Apr. 21, 1914 2 SHEETS-SHEET 2.

COLIUMBIA PLANOGRAPH 60.,WAsHINGTON. D c.

UNITED STATEEiTENT OFFICE.

CONRAD L. DENNIS, OF BUCKLIN, KANSAS.

DEVICE FOR TRISECTING'ANGLES.

To all whom it may concern Be it known that I, CONRAD L. DENNIS, a citizen of the United States, residing at Bucklin, in the county of Ford, State oi Kansas, have invented certain new and useful improvements in Devices for Trisecting Angles; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to devices for tri-; secting angles.

The object of the invention resides in theprovision of a device of the character named through the instrumentality of which a de-: sired angle may be trisected without resort-- ing to any complicated process or mathematical calculation.

A further object of the invention resides,- in the provision of a device of the character; referred to which will be simple in construe-i tion, easily operated and which will produce accurate results.

Vith the above and other objects in view; the invention consists in the details of con--; struction and in the arrangement and com-: bination of parts to be hereinafter more fully described and particularly pointed out in the appended claims. 1

In describing the invention in detail reference will be had to the accompanying drawings wherein like characters of ref-, erence denote corresponding parts in the. several views, and in whichf Figure 1 is a plan view of the movable? member of the device; Fig. 2, a side elevation of what is shown in Fig. 1; Fig. 3, a? section on the line 33 of Fig. 1; Fig. 4, section on the line 44 of Fig.1; Fig. 5, section on the line 55 of Fig. 1; Fig. 6, section on the line 66 of Fig. 1; Fig. 7, a perspective view of the guiding member of the device which is employed in connection with the movable member to render the operation of the latter easier, and Fig. 8, a diagrammatic View showing the manner of utilizing the device to trisect an angle.

Referring to the drawings the device is shown as comprising a body portion 10 in the form of a rectangular plate, same being enlarged at one end as at 11 for a purpose that will presently appear. Mounted upon the body 10 are alined guide members 12 and 13 in which is slidably mounted a bar 14,

Specification of Letters Patent.

Application filed October 30, 1913.

Patented Apr. 21, 1914.

Serial No. 798,279.

said bar running longitudinally of the body 10 as will be obvious upon aninspection of the drawing: l lngaged through the body 10 adjacent the enlarged portion 11 is a bracket 15 to which is secured the inner end of an arm 16 disposed transversely of the body 10. This arm 16 carries a pin or prong 17 disposed at right angles to the arm and against one edge of the body 10. Adjustably mounted upon the bar 14 are clamps 18 and 19 which carry arms 20 and 21 respectively disposed transversely of the body 10. The arm 20 carries at its free end a marking material holder 22 positioned to dispose the marking material carried thereby against the adjacent edge of the body 10. The arm 21 carries at its free end a point 23 disposed against the same edge ofthe body 10 as the marking material carried by the holder 22 and the prong 17. Mount-ed upon the body 10 adjacent the guide member 13 is a finger grip 24, while another finger grip 25 is mounted upon the bar 14 to aid in grasping the latter for the purpose of sliding same in the guide members 12 and 13.

The guide member of the device is indicated generally at A and is shown as formed of a rectangular plate 26 having a lon.gi tudinal slot 27 of a width suflicient to receive the pin 23 and permit free sliding movement of the latter. The plate 26 carries at each end a prong 28 whereby same may be anchored upon a drawing board or the like.

The use of the device can be best illus trated by referring to Fig. 8 wherein the angle X Y Z is to be trisected. The sides of the angle X Y Z are limited by a circle whose center isat the apex of said angle so that the sides X Y and Y Z' constitute radii of said circle. The radius Y Z is then extended indefinitely. The guide member A is then placed across the circle with the slot directly over the radius Y Z and the extension thereof in which position the guide memher is secured against movement by insertion of the prongs 28 in the material beneath. The prong 17 is inserted at the point X and after the arms 20 and 21 have been adjusted soas to be disposed a distance apart of the plate 1.0 the marking material in the holder 22 will intersect the circumference of the circle at the point G, and at the same time the point 23 will be disposed upon the extension of the radius Y Z at the point T. The points X, G and T are then connected by a straight line which is rendered possible by reason of the fact that the prong l7, marking material holder 22 and pin 23 are all disposed in a common line. The angle .G T Y thus had is equal to one-third of the angle X Y Z.

To prove the accuracy of the result conmet the point G and Y: The angle X Y Z equals the angle G T Y plus the angle G X Y by reason of the fact that the exterior angle of any triangle equals the sum of two nonadjacent interior angles. G T equals G Y because G T is the distance between the marker holder 22 and the pin 23 which distance is equal to the radius G Y. Now the angles G T Y equal the angle G Y T (if a triangle is isosceles it is isoangular), X Y equals G Y (being radii of the same circle), the angle G X Y equals the angle X G Y (if a triangle is isosceles it is isoangular), the angle X G Y equals the angle G T Y plus the angle G Y T (an exterior angle of any triangle equals the sum of two non-adjacent interior angles), the angle X G Y equals two times the angle G T Y (things equal to the same thing are equal to each other), the angle G X Y equals two times the angle G T Y (things equal to the same thing are equal to each other), by addition the angle G X Y )lus the angle G T Y equals three times tie angle G T Y, therefore the angle X Y Z equals three times the angle G T Y (things equal to the same thing are equal to each other). By thus taking the intercepted are of a circle having its center at T and the radius Y Z the same can be readily laid out on the arc X Z to effect the division of the angle X Y Z into three parts.

It will be noted that while the use of the guide member A facilitates the operation of the device its employment is not absolutely necessary as the pin 23 can be guided along the line Y Z and the extension thereof and the same result reached.

hat is claimed is 1. A device of the class described com prising a plate having a pivot point upon which same is adapted to rotate, a bar slidable longitudinally on the plate, and a pair of arms adjustable on said bar, said arms being disposed transversely of the plate, a. pin carried on the free end of the arm remote from the pivot point, and a. marking material holder carried on the free end of the arm adjacent the pivot point, said pivot point, marking material holder and pin being disposed in a common plane.

2. A device of the class described comprising a plate'having a pivot point upon which same is adapted to rotate, guide menr bers mounted on said plate. a bar slidable in said guide members longitudinally of the plate, a pair of clamps adjustably mounted on said bar, arms carried by said clamps respectively and extending transversely of the plate, a marking material holder and a pin mounted on the free ends of said arms, said marking material holder, pin and pivot point being disposed in a common plane.

3. A device of the class described comprising plate having a pivot. point upon which same is adapted to rotate, abarslidable longitudinally of the plate, a pair of arms adjustably mounted on said bar and disposed transversely of the plate, a marking material holder and a pin mounted on the free ends of said arms respectively, said marking material holder, pin and pivot point being disposed in a common plane, in combination with a plate having means at each end for securing same against movement to a fixed member and having a slot therein adapted to receive said pin and guide same in a straight line during the rotation of the first named plate.

In testimony whereof, I attix my sigmh ture, in the presence of two witnesses.

CONRAD T1. DENNIS. )Vitnesses W. L. lllivrrnmv, J. N. RIEGEL.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. C. 

